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Homeostasis In Mammals.

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HOMEOSTASIS IN MAMMALS Homeostasis is method by which an organism controls it internal environment. It does this by keeping the level of a number of substances in the body at a constant level (at a set point). If levels of substances move away from that set points then corrective mechanisms take place which restore the level to the set point. In this essay I am going to talk about three types of Homeostasis, these are: glucose regulation, osmoregulation and thermoregulation. Glucose regulation is simply the regulation of the level of glucose in the blood. Thee amount of glucose in the blood is commonly referred to as the blood sugar level. A rise in the blood sugar level (caused, for example by eating a meal) will be detected by the pancreas and the insulin-producing tissue, called the islets of Langerhans release the hormone called insulin, this causes increased absorption of glucose by cells, due to the increased permeability of cell membranes. ...read more.


to become more permeable to water. Because of this more water is reabsorbed into the blood and the level of water in the blood rises. This process works both ways. If the level of water is too high within the body ADH will not be released into the blood causing little re-absorption of water into the blood this causes a dilute urine to be produced, where as a concentrated urine will be produced if there are high levels of ADH in the blood. Thermoregulation is the method by which animals control their internal body temperature. Animals fall into two categories where this is concerned: ectotherms or endotherms. Ectotherms, use external sources of heat, e.g. the sun to raise or maintain there body temperature. Reptiles such as lizards and snakes can often be seen basking in the sun on rocks in order to achieve this control over their body temperature. This method of thermoregulation is not very reliable in some cases as there may be factors that limit the ability of ectothermic animals to regulate their body temperature. ...read more.


In the case of mammals needing to reduce their heat levels (in hot conditions) vasodilatation occurs, this is the opposite of vasoconstriction, blood vessels become wider allowing more blood to flow through, closer to the surface of the skin, thus allowing heat to be lost through the skin due to radiation. Sweating is another method used; the evaporation of water from the skin has a cooling effect on the body. This effect is due to a physical principal. To convert water to a vapour a certain amount of heat is required this is called the heat of vaporization. This heat will increase the speed at which the water molecules move, causing them to escape into the air and cool us down in the process. These mechanisms are mainly controlled by the hypothalamus, which contains temperature receptors that are sensitive to the temperature of the blood. It is this part of the brain that controls mostly all of the homeostasis in mammals. Charles Thompson 5/7/07 ...read more.

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